Like other festivals, Invocation has tents, portable toilets and speakers. But similarities with other events end there.

Organised by the Catholic church of England and Wales, Invocation 2010 is a national festival to recruit monks, nuns and priests to its ranks ahead of the Pope's visit to Britain this autumn.

The first event of its kind to be held in this country, it is expected to attract more than 100 would-be church entrants aged between 16 and 35 to Oscott College in Sutton Coldfield in the West Midlands this weekend.

Young Catholics will be treated to inspirational talks from archbishops, sung complines and an optional midnight rosary. Familiar faces will make an appearance, including Abbot Christopher Jamison, who took part in the BBC series The Monastery, and Sr Gabriel Davison, who featured in the BBC series The Convent.

The organiser, Chris Smith, who works for the archdiocese of Birmingham, said he was expecting more than 400 people.

"What we wanted was a real cross-section," he said. "We have dynamic priests and nuns, we have people training to be priests and nuns. They will be able to share their experiences. This is the first time all the religious communities and dioceses have worked together. Young adults are used to festivals".

Smith described the interest in vocations as encouraging. "The age range of people showing an interest in entering the priesthood or becoming part of a religious community is getting younger. They are now 16, 17 or 18 but 10 years ago they would have been 30 or 40 years old."

There has been a rise in the number of people entering seminaries in England and Wales, from 24 in 2003 to 43 in 2009. This reflects a global pattern. Last year, the Vatican announced that the number of Catholic priests had risen from 405,178 in 2000 to 408,024 in 2007, reversing a two-decade long decline.

In its statistical yearbook, the Vatican said the biggest leaps were in Africa and Asia. The figures were "a continuing trend of moderate growth ... after over two decades of disappointing results," it said.

On a website aimed at men considering a life in the priesthood, the British situation is described as "complex". Ukpriest.org says: "To attribute the lower number of persons entering the priesthood to any single cause would be too simple. The world and the church have undergone dramatic change in the last 30 or 40 years or so. Furthermore, the high number of people entering religious life in the 1950s and 1960s was not typical of most of the church's history.

"Today's lower numbers have been attributed, among other things, to the many changes religious congregations have experienced; growing professional opportunities for men and women; the acceptance of Catholicism into mainstream culture; the reluctance of many people to make permanent commitments of any kind; and an increasing attachment to material goods and social status."